Investment in variable interest entity	12 Months Ended
Sep. 30, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Investment in variable interest entity	Investment in variable interest entity On November 1, 2021, the Company contributed certain assets and licensed certain intellectual property rights to the then newly formed Revelar Biotherapeutics, Inc. (“Revelar”), an independently operated, new biotechnology company, to develop and commercialize an antibody, discovered and optimized by Twist Biopharma, a division of the Company. The Company granted a license to Revelar for the exclusive development of an antibody lead along with a series of back up compounds for the potential treatment of SARS-CoV-2. While the licensed antibody neutralized all known variants of concern through Omicron, it does not neutralize the BA.4 and BA.5 variants. The Company committed to invest up to $10.0 million in seed funding based on Revelar’s progress in the development of the lead antibody and the potential licensing of additional antibody therapeutics, of which the Company made an initial investment of $5.0 million in a simple agreement for future equity (“SAFE”), and two additional investments of $2.5 million each, as described below. In exchange for the assignment of certain contractual rights and the license to the antibody, and its back-up compounds, the Company received stock of Revelar amounting to an ownership percentage as of the date of these financial statements of 49.80%, excluding shares and options reserved for future stock awards and further excluding shares that Revelar would have issued to the Company upon conversion of its SAFEs. On February 3, 2022, the Company purchased an additional SAFE issued by Revelar for $2.5 million pursuant to the Asset License and Contract Assignment Agreement between the parties. In exchange for the SAFE, the Company obtained the right to receive shares of Revelar issued in a future preferred stock financing. On April 6, 2022, the Company purchased an additional SAFE issued by Revelar for $2.5 million pursuant to the Asset License and Contract Assignment Agreement between the parties. In exchange for the SAFE, the Company obtained the right to receive shares of Revelar issued in a future preferred stock financing. The Company determined that Revelar was a VIE as the entity lacks sufficient equity to finance its activities without additional support. Additionally, the Company determined that it has (a) the power to direct the activities that significantly impact Revelar’s economic performance and (b) the obligation to absorb losses of, and the right to receive benefits from, Revelar that are potentially significant to Revelar. As a result, the Company was deemed to be the primary beneficiary of Revelar and is required to consolidate Revelar in accordance with ASC 810; however, the Company deconsolidated Revelar as described below. Revelar incurred a net loss of approximately $14.6 million for the year ended September 30, 2022, and the decrease in net assets was fully absorbed by the Company. The license agreement with Revelar which provided the Company with power to direct Revelar's activities that most significantly affected Revelar's economic performance and caused the Company to have the obligation to absorb or right to receive the majority of Revelar's losses or benefits, was terminated by all parties on September 30, 2022. As a result, the Company assessed its status as the primary beneficiary of Revelar and determined it was no longer the primary beneficiary of the VIE. The Company deconsolidated Revelar as of September 30, 2022. The deconsolidation resulted in a gain of $4.6 million, recorded in “gain on deconsolidation of subsidiary” in the consolidated statements of comprehensive loss in the year ended September 30, 2022 and the Company deconsolidated Revelar's net liabilities of $4.6 million.

On November 1, 2021, the Company contributed certain assets and licensed certain intellectual property rights to the then newly formed Revelar Biotherapeutics, Inc. (“Revelar”), an independently operated, new biotechnology company, to develop and commercialize an antibody, discovered and optimized by Twist Biopharma, a division of the Company. The Company granted a license to Revelar for the exclusive development of an antibody lead along with a series of back up compounds for the potential treatment of SARS-CoV-2. While the licensed antibody neutralized all known variants of concern through Omicron, it does not neutralize the BA.4 and BA.5 variants. The Company committed to invest up to $10.0 million in seed funding based on Revelar’s progress in the development of the lead antibody and the potential licensing of additional antibody therapeutics, of which the Company made an initial investment of $5.0 million in a simple agreement for future equity (“SAFE”), and two additional investments of $2.5 million each, as described below. In exchange for the assignment of certain contractual rights and the license to the antibody, and its back-up compounds, the Company received stock of Revelar amounting to an ownership percentage as of the date of these financial statements of 49.80%, excluding shares and options reserved for future stock awards and further excluding shares that Revelar would have issued to the Company upon conversion of its SAFEs.

On February 3, 2022, the Company purchased an additional SAFE issued by Revelar for $2.5 million pursuant to the Asset License and Contract Assignment Agreement between the parties. In exchange for the SAFE, the Company obtained the right to receive shares of Revelar issued in a future preferred stock financing.

On April 6, 2022, the Company purchased an additional SAFE issued by Revelar for $2.5 million pursuant to the Asset License and Contract Assignment Agreement between the parties. In exchange for the SAFE, the Company obtained the right to receive shares of Revelar issued in a future preferred stock financing.

The Company determined that Revelar was a VIE as the entity lacks sufficient equity to finance its activities without additional support. Additionally, the Company determined that it has (a) the power to direct the activities that significantly impact Revelar’s economic performance and (b) the obligation to absorb losses of, and the right to receive benefits from, Revelar that are potentially significant to Revelar. As a result, the Company was deemed to be the primary beneficiary of Revelar and is required to consolidate Revelar in accordance with ASC 810; however, the Company deconsolidated Revelar as described below.